1) Technical Field
Embodiments herein relate to systems for generating pulsating liquid jets directed at a workpiece and for removal of material from the workpiece in areas thereof impacted by the pulsating liquid jet. Particular embodiments herein relate to fluid jet surgical devices and more specifically to ultrasonically pulsated fluid jet surgical devices for enhanced tissue harvesting suitable for both ablative therapy and for collection of cellular materials such as for regenerative medicine or other purposes.
2) Background Art
The use of basic fluid jets in surgery is well known in the art. These devices can be generally divided into two categories of continuous and pulsated jets. Examples of prior art disclosing continuous jets include U.S. Pat. No. 6,375,635 (Moutafis).
Examples of previously disclosed devices include U.S. Pat. Nos. 3,818,913 and 3,930,505 (Wallach) interrupted jet, does not specify method for interrupting, European Patent EP 0636345 Sentinel Medical, and World Patents Surgical instrument with interrupted stream created by piston pump. Gonon—Interrupted fluid jet utilizing periodic interruption of stream alternating with suction with fluid delivery. WO-2006-026969 Pein and Tork—Continuous water jet with fan shaped pattern and integrated liposuction. WO/2008/074284 Kensy, Winkler et al—Continuous water jet with clear chamber to permit wound care without spray of material. Puchala, R. J. and Vijay, M M, Study of an ultrasonically Generated Cavitating or Interrupted Jet: Aspects of Design, Paper B2, Proceedings of the 7th International Symposium on Jet Cutting Technology, Paper B2: 69-82, 1984. Vijay, M M, Foldyna J, Remisz J, 1993.
Continuous flow water jets have several disadvantages. First, they rely upon stagnation pressure or erosive pressure of the fluid stream. The skilled practitioner will recognize that this leads to inefficient tissue disruption, the need for high pressures to effect tissue disruption, and potential unintended injury to tissues in the path of the fluid jet. Additionally, this additional pressure results in widespread cellular injury, rendering the aspirate unsuitable for use in regenerative medicine as a source of viable cells and tissue for engraftment. Examples of this approach include ((Moutafis)) which relies upon the delivery of a continuous fluid jet into the orifice of a suction tube. In order to ablate tissue, the stream is passed tangentially across the desired tissue, and suction draws the target tissue into the stream. The skilled practitioner will further recognize that devices of this design are bulky, relatively inefficient at tissue ablation, and unsuited to many types of surgery.
Later devices introduced interrupted fluid streams which were more efficient at tissue ablation. These devices have relied upon periodic interruption of a fluid jet to increase tissue destruction. The speed with which the fluid stream can be interrupted with mechanical devices is limited, however, resulting in inefficient droplet or slug formation, and permitting only an incremental increase in efficiency of tissue harvest. Further, at the frequencies and volumes attainable with these types of devices, the practitioner will recognize that tissue-specific tailoring of the frequency of the pulsation is unattainable.
Hansell, June 1950, disclosed a Jet Sprayer actuated by supersonic waves which relied upon but this device was generally unsuccessful.
Current technology for transplanting mesenchymal stem cells (MSCs) for cellular therapy utilizes conventional liposuction. Adipose tissue has thousands of fold more MSCs than other mesenchymally derived tissues. These cells are present in all adipose tissue, and can be used for reinjection either with or without further manipulation, culture, growth factors, etc, to regenerate tissues.